Humidifying Flutes




I'm often asked about humidifying flutes.  Lots of questions - do they need it, why do they need it, how should I do it, are there risks, etc.  I'll try to answer those questions here.

Do flutes need humidification?

It will depend on the flute and the conditions you're keeping the flute in. If it's generally in an unheated room, in a normal climate, it's probably going to be fine as it is. But modern heating and air conditioning dry out the air, especially when desert or snow has already taken out most of the moisture already!

Some flutes normally won't need humidification.  For example, flutes without tuning slides should be fine in any climate.  So should flutes using my New Improved Tuning Slide.  It's flutes that have metal tuning slides firmly encased in the wood of the heads and barrels that are at most risk in low humidity.  Unfortunately, that includes most of the flutes in use in Irish music today.

Watch out also for flutes with metal reinforcing rings on the tips of the tenons.  I've come across quite a few flutes where the socket has shrunk enough to imprison the tenon ring, while at the same time, the tenon has shrunk enough to release it.  I've even come across flutes where the socket has cracked because of the imprisoned ring. 

Why do flutes need humidifying?

Consider what happens to a flute when the weather dries out for a long time.  Maybe your flute was made in 19th century London, in a probably unheated or partially heated workshop.  (Do you think we might run to a second lump of coal this winter, Mr Rose?)  Or maybe it was made more recently in Ireland, or in a pleasantly warm and humid part of the US.  But you've just moved to Maine, or Colorado, or your new London flat has central heating in winter or year-round air conditioning.  The flute was made at 65%RH, but now lives at 20% or less.  Its only hope of respite comes when you blow your dank, alcohol laced breath into it, but, even then, the tuning slide metal prevents the life-saving drops soaking into the wood.  So near, and yet so far!  So the wood shrinks, but the metal doesn't, the stresses build up until ... crack!  Ahhh, that's better.  Relief for the wood, but not for the flute.

But I mean really dry!

Even flutes normally immune from slide damage can run into another problem in dry climates, eg New Mexico, outback Australia, or even a long harsh winter in Scandinavia.  If wood shrinks enough, you can expect rings to come loose.  And loose rings are a danger - assemble a tight joint with loose rings and you risk splitting the socket wood. 

Loose rings are perhaps a good warning signal for owners of flutes with encased tuning slides.  If the wood has shrunk enough to release the rings, it must be getting pretty tight on that tuning slide!

There is also a possibility, oft suspected but as yet unproven, that a flute's performance benefits from increased humidity in the wood.  If it's true, it seems reasonable.  Damp wood is heavier than dry wood, and less porous, and perhaps even effectively smoother to the flow of air across it.  If we improve the "container for air", we improve the flute's performance.  This might be an argument to humidify flutes that are at no risk.

How to humidify

Humidifying a flute isn't hard - all you need to do is introduce a small amount of water safely.  By safely, I mean don't have anything wet in contact with the wood of your instrument or case, or the case fabrics.  And by a small amount of water, I mean a few drops at a time.  It's very easy to over-humidify a flute - and if you do, you'll see how quickly and dramatically it reacts. You'll soon have swollen, tight joints, and run the risk of mould - not a good thing for a flute player to be breathing in! You'll find that just a few drops of moisture are enough to keep the humidity up. Look at the commercially available Dampits - there isn't a lot of capacity in there!

Consider also that we are trying to minimise stress on the flute - violent vacillations between dry and wet doesn't sound like minimised stress.  Softly, softly ...

The Poor Person's Humidifier

I haven't tried this myself, but a few players I've mentioned it to have reported success.  Peel an orange, and eat the flesh.  (Now that wasn't so hard was it?)  Now put the fresh orange peel in the case with your flute.  In a few days those loose rings should be tight again.  Once the orange peel is dry, you'll need to eat another one ....

Another Poor Person's Humidifier

This one I can vouch for.  I was monitoring the weight gain (moisture intake) of my own playing flute during and after sessions, and was surprised to find that the greatest weight gain occurred between mopping out the flute at the end of the session and a few days later when I checked the weight again.  Huh?  The flute was in the case all that time!  Took me a while to realise that the moisture was migrating from the damp mopping rag back to the flute.  Moral of the story - play your flute regularly and leave the mop in the case and the flute won't dry out.  If you can't play it, at least dampen the mop cloth from time to time.

Incidentally, this is not an argument for not mopping out your flute after playing.  Do that, and the moisture lies in pools, soaking unevenly into the flute, raising the grain and possibly leading to cracking.  Very bad!  But when the moisture migrates back from the cleaning rag, the water vapour permeates the case, the fabrics and the flute, and so localised stresses are avoided.

Wooden or plastic case?

Popular advice often includes relocating your flute to a Tupperware container.  I think this advice stems from an overestimate of the amount of water we need to reintroduce.  I'd prefer to keep the flute in a wooden case.  The case will buffer the temperature and humidity changes that each day throws at the flute.  Softly, softly ...

How much humidification?

Because of the risk of over humidification (swollen joints, mould), I always recommend incorporating a hygrometer in with the humidifier, and adjusting the humidity to somewhere around the 50-60% mark (for 19th century flutes) or to whatever level your maker recommends (for modern flutes).  As I mentioned, my flutes shouldn't really need humidification unless the climate is dry enough to loosen the rings, or you feel moved by the "plays better damp" theory.  Given humidity at Malua Bay averages around 50%, that would seem a good number to aim at.

Cheap hygrometers (from cigar stores, or woodworkers' suppliers) tend to be a bit "all over the place", easily varying 30% either way.  Ask to see their best hygrometer, note the current reading, then buy a cheap one that reads the same!

Or prise the back off the hygrometer, and you'll probably find a fine spiral spring connected at its outer end to a thin flat bent-up plate.  The plate in turn is secured to the back of the dial, typically by a dob of goup at one corner of the plate.  Carefully lift the edge of the plate, breaking the hold of the goup, and you'll find you can turn the plate to adjust the hygrometer to read anything you want.  Find out the current RH from another hygrometer or today's local weather report, and set the hygrometer accordingly.  Monitor it for a few days, and when you are confident you are in the right ball park, secure the adjustment with a dob of glue in the corner of the plate.  I did this to one a few years back and it still tracks my laboratory hygrometer amazingly well.

I was impressed to see that the Dampit people have also recognised and responded to the need for measurement, and come up with a pretty cheap way to do it.  I imagine their card is based on the use of cobalt chloride, a crystalline salt which changes colour depending on the RH at the time.  I remember when I was young painting a landscape, using cobalt chloride for the sky.  On a nice sunny day, the sky would be blue, but when rain threatened (i.e. the RH went up), the sky would turn pink.  These days we probably don't want our kids splashing around in cobalt salts!


Humidification is probably warranted anywhere the humidity in which your flute lives drops below 30% for periods in excess of a few weeks.  It's certainly warranted if you know your flute is likely to be badly affected by long spells of low humidity - eg if it has a tightly encased tuning slide, and was made in a damp climate such as Ireland or London.  Loose rings and tightening joints can be taken as a warning sign.

Because it is easy to over-humidify, and there are risks of doing so (eg mould, swollen joints), it pays to introduce the humidity in a very controlled way, and monitor the results closely.  Probably the easiest way to achieve that is the use of the Dampit clarinet humidifier and their indicator card.  If nothing else, try the orange peel!

I've tried to answer the most common questions on this topic, but if there are others bothering you, make sure to get in touch!


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  Created 26 December 2010